First Bus, part of transport company FirstGroup, is investing £77.7 million in 385 new buses, of which 90% will be fitted with ultra-clean Euro 6 engines.

The Wrightbus company, based in Ballymena, Co Antrim, is manufacturing 248 of the buses while ADL, based in Falkirk in Scotland, has secured an order for 117 buses.

In addition, Volvo is building 20 double-decker chassis in Sweden, with the bodies manufactured by Wrightbus.

The investment includes two "virtual electric" (part-hybrid, part-electric) buses, which will enter service in Bristol from December, while five double-decker buses, scheduled to operate in Stirling in Scotland, will be fitted with flywheel technology originating from Formula 1.

All the new buses will be delivered during the current financial year. All will have free wi-fi and leather seats.

First Bus managing director Giles Fearnley said: "This is great news for First Bus customers across the UK. In five years we've invested around £385 million in new vehicles.

"I'm delighted the overwhelming majority of our new vehicles will be fitted with Euro 6 engines. The advances in engineering are remarkable and our investment represents one of the most environmentally friendly bus orders ever placed."

Among towns and cities getting the new buses are Bradford, Glasgow, Halifax in Yorkshire, Slough in Berkshire, Swansea, Leicester and Southampton.